From Vine to Bottle at Stone Hill Winery
Winemaking is both an art and a science. At Stone Hill Winery, harvesting grapes is just the beginning!
Photos by George Denniston for Stone Hill Winery
Download Winemaking Story
In Missouri grapes ripen from mid-August through mid-October depending on the variety. The vast majority of Stone Hill's grapes are machine harvested.
The machine has several advantages over hand harvesting:
- Machine harvesting can be done at night when the outside temperatures are lowest, thereby minimizing the extraction of phenolic compounds. Phenols can impart a bitter taste to delicate white and rosé wines and, therefore, need to be minimized;
- Machine harvesting is much quicker than hand harvesting; therefore, it can be accomplished when the grapes are at their optimum ripeness. One machine harvester can take the place of 50 hand pickers and can harvest up to 1.5 acres per hour;
- In the advent of stormy weather, the machine harvester allows the winery to rapidly harvest before the onset of detrimental late-season bunch rots, which would reduce the quality of the grapes;
- The fruit is very clean since the machine harvester has suction fans over the conveyors, which remove any leaves from the fruit.
Hand Sorting Grapes
A key part of Stone Hill's machine harvesting operation is hand sorting to guarantee maximum quality. As the grapes are discharged from the harvester into the transport bins, they first fall onto a table that fits over the top of the transport bin.
Our crew carefully removes any MOG (Material Other than Grape), ensuring that only grapes are sent to the winery for crushing.
Hand Harvesting Grapes
Most of Stone Hill's Norton grapes are grown on a Y-shaped trellis called the Geneva Double Curtain. Unfortunately, due to the long cluster stem of the Norton grape, mechanical harvesters are not able to adequately harvest Norton grown on this trellis. Therefore, we employ the time-honored tradition of hand harvesting on these vineyards. All of our newer plantings of Norton are being established on a higher-density, single-curtain trellis that will allow for optimum sunlight exposure for maximum Norton quality while also allowing for mechanical harvesting.
Once harvested, the bins of grapes are quickly transported to the main winery in Hermann. The one-ton bins are dumped into a receiving hopper that conveys them to the destemmer/crusher. The destemmer/crusher gently removes the berries from the cluster stem and then slightly crushes the berry to allow for the easy extraction of the juice. From the crusher, the mix of juice, pulp and seeds known as the "must," is pumped through a must chiller to lower the temperature. Must destined for white or rosé wines will go directly to the presses. Reds will go directly to a fermentation tank to be fermented on the pigment containing grape skins. In either case we want the must temperature relatively cool at this stage of the process for optimum quality.
Red Wine Fermentation
At Stone Hill Winery we use different strains of yeast for the different wine types. Each yeast strain has been selected based upon its fermentation characteristics, which can affect the final wine flavor. The yeast is added to the red wine fermentor as it is being filled from the destemmer/crusher. All of our fermenting tanks have refrigeration to control the heat given off by the fermentation and to maintain the fermentation at the optimum temperature for the particular wine. Most of the reds are fermented in the range of 65-75 degrees Fahrenheit. Within a few hours of the onset of active fermentation, the carbon dioxide gas given off by the yeast will cause a cap of grape skins to rise to the top of the fermentor. Twice a day we pump some of the liquid from the bottom of the tank over the top of the cap to remix it and aid in the extraction of pigments and tannins from the grape skins. During this pump-over, the red wine may be splashed through the air to aerate the yeast. Yeast requires a certain amount of oxygen for healthy growth and good fermentation odors. This is one of the few times that oxygen is beneficial to wine quality. After the skin fermentation, the wine is drained from the fermentation tank, and the remaining solids, called "pomace," is pumped to the presses to extract the last of the wine.